Angled hole ventricular catheter with non-circular bore

ABSTRACT

A catheter for placement into the ventricular system of the brain or any other member or cavity of the body of a subject comprising a flexible elongated body having a non-circular bore, a wall thickness sufficient to contain and transport fluid therein, a forward end and tip for insertion into the ventricular system of the brain of a subject, and a plurality of spaced apertures located in the forward end of the body spaced from the tip. The apertures are configured and positioned to minimize abrasion of brain tissue upon insertion of the catheter and to prevent tissue from growing into the catheter apertures, thereby providing improved flow of fluid into or from said ventricular system. The non-circular bore, preferably triangular, provides increased structural integrity and increased effective flow through the catheter compared to those having a circular bore. Also methods of using such catheters are disclosed herein.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.098,097 filed Sep. 17, 1987 now U.S. Pat. No. 4,784,638.

TECHNICAL FIELD

The present invention relates to a catheter having specifically angledapertures and a non-circular bore which facilitate access to or drainageof fluid within or from a host.

BACKGROUND OF THE INVENTION

The four ventricles of the human brain are interconnected cavities thatproduce and circulate cerebral spinal fluid (CSF). Procedures involvingventriculostomy, i.e., placement of a catheter into the ventricularsystem of the brain, form a major part of a neurosurgeon's clinicalpractice. General areas of application of ventricular catheter placementinclude intracranial pressure monitoring (ICP), draining or shunting ofCSF and the instillation of pharmacological therapeutic agents.

CSF drainage is essential for patients with congenital or acquiredhydrocephalus. CSF drainage, which can only be performed with anintraventricular catheter, is a life-preserving procedure, because itcan immediately reduce intracranial pressure. The ventricular catheter,used to drain CSF, is connected to a peripheral subcutaneous drainagesystem, i.e., to the peritoneal cavity or systemic circulation via theheart or in the case of ICP to an external drainage collection system.Standard procedures for ventricular catherization are disclosed in thetextbook literature. See, for example, Neurosurgery, edited by Robert H.Wilkins and Setti S. Rengachary, Section A, Chapter 13, Techniques ofVentricular Puncture (McGraw Hill 1984).

The most frequently chosen site for ventricular catheterization iscoronal. In most cases, a catheter is inserted in the anterior horn ofthe lateral ventricle through an orifice or burr hole drilled justanterior to the coronal suture in the midpupillary line of the cranium,i.e., in the frontal bone over the ventricle. This is known in the fieldas Kocher's point. The burr hole, only slightly larger than the diameterof the selected catheter to insure a snug fit and provide a seal againstCSF leakage, is placed approximately 1 cm anterior to the coronalsuture, approximately 10 to 12 cm above the nasion, and approximately 2to 3 cm from the midline over the nondominant hemisphere. After the burrhole is made, the dura and underlying pia-arachnoid are opened andcoagulated, for example, with a fine-tipped blade after cauterizing thedural surface.

The lateral ventricles of the human brain form an arc parallel to thearc of the cranium, i.e., the contour of the lateral ventriclesparallels the arc of the surface of the skull. Thus, a catheter guidedperpendicular to the cranial surface at the point of entry into thecranium will enter the ventricular system. Specifically, any linepenetrating a burr hole in the surface of the skull at a 90° angle alsobisects the lateral ventricle.

A more recently developed procedure to ensure correct catheter placementis disclosed in U.S. Pat. No. 4,613,324. The apparatus comprises a guideassembly which, when positioned over an orifice drilled in the craniumabove the anterior horn of the lateral ventricle, guides a catheter andobturator through the orifice and into the lateral ventricle at an anglenormal to an imaginary plane formed by a tangent to the cranium at theorifice, while the corresponding method comprises providing an orificein the cranium just anterior to a coronal suture in a midpupillary lineof the cranium and inserting a ventricular catheter containing anobturator through the orifice towards a lateral ventricle, wherein thecatheter containing the obturator is guided through the orifice, bymeans of a novel guide assembly, at an angle normal to an imaginaryplane formed by a tangent to the cranium at the orifice.

A wide variety of catheters are known in the prior art for the purposeof penetrating the ventricular cavity. Such catheters are typically inthe form of a hollow tube with a circular bore which is provided with aplurality of apertures at the ventricular or inflow end to permit thepassage of CSF from the brain into the catheter and thence to thebloodstream or peritoneal cavity of the patient or to an externaldrainage system. However, malfunctions frequently occur with such acatheter due to the blockage of the apertures in the inflow end of thecatheter. Such blockage is usually caused by the growth of choroidplexus or ependymal tissue within the ventricle into the apertures inthe inflow end of the catheter. This tissue may block the apertures inthe inflow end of the catheter in a relatively short period of timeafter the catheter has been inserted into the ventricle therebyrendering the cathether inoperative in relieving excess pressure due tothe build-up of CSF within the ventricle. Furthermore, prior artcatheter apertures are cut perpendicular to the length of the catheter,thus causing abrasion of brain tissue when the catheter is inserted.

The likelihood of ventricular catheter malfunction by aperture pluggingwith brain tissue can be lessened by angling the aperture holes in thewall of the catheter such that there is "no see through" flow from theoutside to the inside of the lumen. Also, by positioning the rows ofapertures 120° apart there is essentially no chance for direct ingrowthof ventricular tissue therethrough. In addition, the apertures areangled away from the direction of the insertion of the catheter into thebrain thus lessening the chance of brain abrasion. Further, by slightlystretching the catheter by means of the stylet (which is integral to thecatheter and used for placement of it into the brain) the holes willclose so that no opening will be visible during the placement thereof,with the holes re-opening after the tension on the catheter is relievedby removal of the stylet.

A catheter may also malfunction by kinking due to insufficientstructural rigidity. Kinking may cause blockages or ineffective flowpaths within the catheter, thereby rendering it inoperative in relievingexcess pressure due to the build-up of CSF within the ventricle. Inaddition, kinking may cause the catheter to wander off course and makethe insertion more difficult for the neurosurgeon and more harmful tothe patient. The likelihood of the catheter kinking can be lessened byusing a non-circular bore which will increase structural rigidity andstrength.

As such, it would be desirable to provide a catheter which overcomes theproblems of previously devised ventricular catheters which areemplaceable within a ventricle of a human brain to control the flow ofexcess fluids to or from the brain. The present invention provides asimple solution which resolves the problems of prior art catheters in anovel and unexpected manner.

SUMMARY OF THE INVENTION

The present invention relates to a catheter for placement into a hostfor accessing fluid therein, preferably for insertion into theventricular system of the brain of a subject to access CSF. Thiscatheter comprises a flexible elongated body with a non-circular borehaving a wall thickness sufficient to contain and transport fluidtherein. The body has a forward end and tip for insertion into theventricular system and a plurality of spaced apertures located in theforward end of the body spaced from the tip. Each of the aperturesextends through the wall thickness at an angle such that a portion ofthe wall thickness is visible when viewing the aperture perpendicular tothe axis of the body. This arrangement facilitates closure of theapertures by slightly stretching the body with a placement stylet tominimize abrasion of brain tissue upon insertion of the catheter. Thisarrangement also helps prevent choroid plexus tissue from growing intothe catheter apertures, thereby providing improved flow of fluid into orfrom the ventricular system.

Preferably, each of the apertures extends through the wall thickness atan angle of about 35° with respect to the longitudinal axis of the body,and a plurality of apertures are aligned in a number of rows. Also, rowsof these apertures are spaced 120° apart around the circumference of thebody for maximizing the structural integrity of the catheter forwardend.

The body of the catheter is provided with a bore to transport fluidsinto and out of the brain. In order to increase the structural integrityand the effective flow area of the catheter, as compared to a circularbore catheter, a bore in the form of a polygon, and preferably, in theform of an equilateral triangle is employed.

If desired, the forward end of the body can be made of a radioopaquematerial at least in the area surrounding the apertures to facilitatemonitoring of catheter placement. The body may include means to indicatethe depth of penetration of the catheter forward end to assist in properplacement thereof. These depth penetration indication means may bemarkings of a radioopaque material to facilitate monitoring of theplacement of the catheter.

The invention also relates to method of accessing CSF in a ventriclewithin a human cranium which comprises drilling an orifice in thecranium just anterior to a coronal suture in a midpupillary line of thecranium, and guiding a catheter through the orifice by means of a guideassembly in a direction perpendicular to an imaginary plane defined by atangent to the cranium at the orifice. The catheter thus accuratelypenetrates the ventricle on the first insertion with minimal abrasion ofbrain tissue. The catheter, described above, i.e., one having theappropriate positioning and configuration of apertures to minimizeventricular tissue growth thereinto, is preferred so that increased flowof fluid to or from the ventricle is obtained.

The catheter of this method utilizes a guide assembly comprising tubularmeans and support means for the tubular means. Therefore, the methodfurther comprises placing the support means so as to rest unsecured onthe human cranium in surrounding spaced relation to the orifice, andguiding the catheter through the tubular means, into the orifice andinto the ventricle. The support means and tubular means are related toeach other such that the catheter is guided through the orifice by thetubular means in a direction perpendicular to an imaginary plane definedby a tangent to the cranium of the orifice, independent of the orifice.To accomplish this, the tubular means is supported through a supportmeans comprising a plurality of legs of equal length.

Also, this method further comprises inserting a removable insert withinthe tubular means to reduce the diameter thereof for receiving thecatheter. A stylet may be utilized to assist in the insertion of thecatheter in a manner such that the catheter is stretched so as toflatten the apertures to further reduce abrasion of brain tissue uponinsertion therein. In a preferred arrangement, the catheter bodyincludes means for indicating the depth of penetration of the catheterforward end so that the method further comprises inserting the catheterto a predetermined depth into the ventricle. The indicating means may beradioopaque markings so that the placement of the catheter in theventricle can be monitored.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described hereinbelow withreference to the drawing figures wherein:

FIG. 1 is a perspective view of a catheter according to the invention;

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1; and

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIG. 1 there is illustrated catheter 10 which isintended for insertion into a ventricle of the human brain for access toor drainage of CSF such as; for example, would be necessary to drainexcess CSF during treatment of hydrocephalus. Since the presentinvention is primarily concerned with the forward or insertion end ofthe catheter, a detailed description of the opposite or out flow end ofthe catheter is not provided as such details are well known in therelevant surgical art.

This catheter 10 is a flexible, hollow, elongated member having asufficient wall thickness for the containment and or transport of fluidstherein and therethrough. The forward end 12 of the catheter includes aplurality of apparatus 14 for access to CSF in the ventricle of thebrain. By "access" what is meant is contact of CSF for removal ordrainage from the brain or, conversely, to enable medicaments or otherfluids to be directed or delivered into the brain from the catheterthrough the apertures 14. These apertures 14 are positioned andconfigured in a predetermined manner so as to allow for a better andmore continuous flow of fluids in and through the catheter with lesschance of plugging the holes due to ingrowth of a brain tissue when thecatheter is placed in the ventricle. Further, the design of the holesenables the catheter placement to be made in an improved, easier mannerwhile causing less abrasion damage to tissue during insertion of thecatheter.

As shown in FIG. 2, the catheter 10 is designed with a bore in the shapeof an equilateral triangle 18. This shape is preferred over a circularshape because it provides 1.7 times the effective flow area whileproviding additional structural integrity. Further, this shape caneasily be partitioned to allow the formation of secondary lumens to runother implements into the ventricle, within the main lumen whilemaintaining sufficient flow area.

As shown in FIGS. 2 and 3, the catheter 10 is designed with 3 sets ofholes set 120° apart, the centers of which coincide with the midpoint ofeach side of the triangular bore 18. These holes are cut at an angleinto the wall of the catheter such that the angle of the cut is measuredalong the longitudinal axis of the catheter in the direction of movementof the catheter when it is inserted into the ventricle. Further, thediameter of each hole in the catheter is proportional to the thicknessof the catheter wall so that, as best illustrated in FIG. 3, there is nodirect linear visual access to the interior of the catheter when theholes are viewed perpendicular to the longitudinal axis of the catheter.

By preparing the holes in this manner, abrasion of brain tissue isminimized upon insertion of the catheter into the ventricle, so lessbrain tissue is destroyed as a direct result of such decreased abrasion.Further, by stretching the catheter slightly, the holes in the catheterare closed thus preventing such tissue as may come in contact with thecatheter from entering the lumen upon insertion. The stretching of thecatheter can easily be accomplished when a rigid placement stylet isused: the body of the catheter being slightly pulled back from theinsertion end while the stylet is held, thus allowing the holes to besomewhat flattened. This lack of direct access to the inside of thecatheter prevents the growth of brain cells or tissue therein, thusresolving one of the major causes of plugging and malfunction of priorart catheters which utilize 90° or perpendicular apertures. The 120°peripheral offset for each set of holes further minimizes thepossibility that choroid plexus or brain cell growth will extend acrossthe inner diameter of the catheter even if such growth does penetrateinto one or more of the holes.

Although the holes are advantageously shown as being cut at an angle of35° with respect to the longitudinal axis of the catheter, it is to benoted that other angles can also be used in this invention provided thatdirect access to the inside of the catheter is prevented. These otherangles would be somewhat dependent upon wall thickness of the catheter,since heavier wall thicknesses would allow a greater range of angleswhile still preventing direct access into the catheter interior.Suitable angles for any specific catheter construction can be determinedfrom the relationship d=t/tanθ, where d is the diameter of the aperture,t is the wall thickness of the catheter, and θ is the angle between thecut of the aperture and the longitudinal axis of the catheter body. Asshown by the relationship of these variables, the diameter of theaperture must be less than or equal to the wall thickness of thecatheter divided by the tangent of the angle. To calculate suitableangles for any particular aperture size and catheter wall thickness, theformula would be θ=tan⁻¹ t/d , so that the tangent of the angle, θ isgreater than the quotient of the thickness divided by the diameter.

To assist in the understanding of the invention, direct access isavoided when the diameter of the hole on the outside wall of thecatheter does not overlap the diameter of the hole on the inner wallcatheter when viewed in a line perpendicular to the wall of thecatheter. Thus, it is possible to utilize angles other than 35° although35° has been found to be particularly advantageous.

By placing the holes to avoid direct access to the inside of thecatheter, it is possible to cut the holes larger in diameter than theywould be if direct access was provided without weakening the structuralintegrity of the catheter. These larger holes allow for an increasedflow of CSF into the catheter while also making it more difficult forany possible brain cell growth to plug the entire hole, compared to therelatively smaller diameter holes of prior art catheters which providedirect access into the body of the catheter.

The catheter of the invention can be inserted into the ventricle of thebrain in any manner currently known, including "freehand" or with theuse of a guide. To assist in the proper location and placement of thecatheter, a plurality of markings 16 are provided along the length ofthe catheter body. These markings correspond to predetermined insertionlengths of the catheter and enables the surgeon to know precisely howfar the tip of catheter is inserted into the ventricle By making thesemarkings of a radioopaque material such as barium, the depth ofplacement of the catheter can easily be monitored by conventionaltechniques. Furthermore, if desired, the forward section of the catheterin the area around the apertures can also be made of a radioopaquematerial for viewing on various scanning equipment the precise placementof the forward end and tip of the catheter.

The improvements provided by the catheter of this invention aresignificant in that the physician does not require any guess work todetermine the precise placement of the catheter in the patient's brain.Furthermore, when so placed, the catheter provides improved fluiddelivery and/or removal with minimal disturbance of the surroundingbrain cells while also discouraging brain tissue growth into thecatheter apertures. As mentioned above, the catheter can be inserted inthe brain in any manner commonly utilized. Rather than a "free hand"technique, it is advantageous to utilize a guide assembly to insurecorrect catheter placement.

One method of accessing the ventricle is by drilling a hole in the skullby using a manual twist drill and supporting guide. After drilling thehole, the drill guide can be converted to a catheter guide by use of aninsert. This method and the apparatus associated therewith are disclosedin U.S. patent application Ser. No. 093,426, Sep. 4, 1987, the contentof which is expressly incorporated herein by reference thereto.

Another preferred guide apparatus and method of insertion of a catheterinto the ventricle is disclosed in U.S. Pat. No. 4,613,324, thedisclosure of which is expressly incorporated herein by referencethereto. As shown in the patent, a stylet is used to assist in theinsertion of the catheter. As noted above, the stylet can be used tostretch the present catheters so that the angled apertures can beflattened to minimize the abrasion of brain tissue during insertion.Also, this flattening operation slightly reduces the overall diameter ofthe catheter which further reduces such abrasion.

It is known for certain applications to utilize a second stylet forguiding the catheter into the ventricle. In prior art catheters, thissecond stylet is inserted into one of the apertures at the forward endof the catheter. Since those apertures are cut at 90° an unwieldyassembly is created. Any attempt to align the second stylet parallel toand adjacent the first stylet and catheter causes the tip to be somewhatbent, thus causing further difficulties in its insertion and penetrationof the ventricle. The present invention significantly reduces andminimizes this problem since the angled holes are more receptive to theintroduction of the second stylet in a compact orientation (i.e., in a"V" shape, rather than an "L" shape) which greatly enhances themanipulation of the catheter and stylets during placement in theventricle.

Prior art catheters, as noted above, have four sets of holes oriented90° apart along the circumference of the catheter. In addition toweakening the strength and structural integrity of the catheter in thetip area, holes on opposite sides of the catheter (i.e., those 180°apart) are made simultaneously by a punching tool. This results in holeson one side being larger in diameter than those on the opposite side.Therefore, two sets of holes are large and two are small. Thisnon-uniformity affects CSF flow and the smaller holes can easily becomeblocked by brain tissue growth, thus causing reduced operation of thosecatheters.

The present invention resolves these problems by accurately andprecisely placing three sets of uniform holes cut at the desired angleto the catheter body and spaced apart exactly by 120°. This results inincreased flow through the holes, higher strength and integrity of thecatheter body, and greater ease of insertion and placement of thecatheter in the ventricle.

While it is apparent that the invention herein disclosed is wellcalculated to fulfill the objects above stated, it will be appreciatedthat numerous modifications and embodiments may be devised by thoseskilled in the art, and it is intended that the appended claims coverall such modifications and embodiments as fall within the true spiritand scope of the present invention.

What is claimed is:
 1. A catheter for placement into a host comprisingaflexible elongated body having a wall thickness sufficient to containand transport fluid therein and having a forward end and tip forinsertion into the host; a plurality of spaced apertures located in saidforward end of said body spaced from said tip and positioned so as tominimize abrasion of tissue upon insertion of said catheter into saidhost; and said body having an internal bore having a non-circular crosssection to increase the structural integrity and effective flow area ofthe catheter compared to those having a circular cross sectional bore;wherein each of said apertures extends through the wall thickness at anangle such that a portion of said wall thickness is visible when viewingsaid aperture perpendicular to the axis of said body.
 2. The catheter ofclaim 1 wherein each of said apertures extends through said wallthickness at an angle of about 35° with respect to the longitudinal axisof said body.
 3. The catheter of claim 1 wherein said apertures arealigned in rows which are spaced about 120° apart around thecircumference of said body.
 4. The catheter of claim 1 wherein the crosssectional area of the bore is a polygon, and wherein said apertures arepositioned along the midpoint of each side of said polygon.
 5. Thecatheter of claim 4 wherein an inner bore surface of said catheter issubstantially smooth and free of any projections extending into saidbore.
 6. The catheter of claim 1 wherein said forward end of said bodyis integrally formed of a radioopaque material at least in the areasurrounding said apertures to facilitate monitoring of the placement ofsaid catheter within said host.
 7. The catheter of claim 6 wherein saidbody further comprises means to indicate the depth of penetration ofsaid catheter forward end.
 8. The catheter of claim 7 wherein said meanscomprises markings of a radioopaque material to facilitate monitoring ofthe placement of said catheter.
 9. A catheter for placement into theventricular system of the brain of a subject comprising:a flexibleelongated body having a wall thickness sufficient to contain andtransport fluid therein and having a forward end and tip for insertioninto the ventricular system of the brain of a subject; and a pluralityof spaced apertures located in said forward end of said body spaced fromsaid tip, each of said apertures extending through the wall thickness atan angle such that a portion of the wall thickness is visible whenviewing said aperture perpendicular to the axis of said body so as tominimize abrasion of brain tissue upon insertion of said catheter and tohinder the growth of brain tissue into said catheter apertures therebyproviding improved flow of fluid into or from said ventricular system;said body having internal bore of a polygonal cross-section to increasethe structural integrity and effective flow area of the cathetercompared to those having a circular cross-sectional bore.
 10. Thecatheter of claim 9 wherein the cross-section of the bore is triangular,and wherein said apertures are positioned along the midpoint of eachside of the triangle.
 11. A method of accessing fluid within a hostwhich comprises: providing a cateter comprising a flexible elongatedbody having a wall thickness sufficient to contain and transport fluidtherein and having a forward end and tip for insertion into said host,and a plurality of spaced apertures located in said forward end of saidbody spaced from said tip, each of said apertures extending through thewall thickness at an angle such that a portion of said wall thickness isvisible when viewing said aperture perpendicular to the axis of saidbody; inserting said catheter into said host while minimizing abrasionof tissue therein; and increasing the flow of fluid to or from said hostby minimizing or preventing tissue growth into said catheter aperturesthrough the position and configuration of said apertures in saidcatheter.
 12. The method of claim 11 which further comprises selecting acatheter having a bore configured of a non-circular cross-section toincrease the effective flow of fluid through the catheter and toincrease the structural integrity of the catheter compared to thosehaving a circular bore and further wherein the non-circular crosssection is such that it prevents a flow restriction where said catheteris bent.
 13. The method of claim 12 which further comprises providingthe catheter with a bore said which is configured of a cross sectionhaving the form of an equilateral triangle and wherein said aperturesare aligned in rows spaced about the circumference of said body at 120°intervals to coincide with the midpoint of each leg of said triangle.14. The method of claim 11 which further comprises utilizing a stylet toassist in the insertion of said catheter in a manner such that thecatheter is stretched so as to flatten said apertures to further reduceabrasion of tissue upon insertion therein.
 15. The method of claim 11wherein said catheter body further comprises means for indicating thedepth of penetration of said catheter forward end and wherein saidmethod further comprises inserting said catheter to a predetermineddepth.
 16. The method of claim 11 wherein said indicating meanscomprises radioopaque markings and wherein said method further comprisesmonitoring the placement of said catheter.
 17. The method of claim 11wherein cerebral spinal fluid in a ventrical within a human cranium isaccessed by drilling an orifice in the cranium just anterior to acoronal suture in a midpupillary line of the cranium prior to insertingsaid catheter into said ventricle.